The present invention relates to an apparatus for the throttling or restricting of flow in water fittings, particularly sanitary fittings, with a throttling insert made from an elastic material and supported against an annular shoulder having a flow opening, which is bounded on the inflow side by a regulating lip, which increases or decreases in size the entry cross-section of the flow opening as a function of the pressure of the water flowing through. Such an apparatus is described in Offenlegungsschrift 1650209, dated Sept. 10, 1970.
In the hitherto known means of this type, particularly in the higher delivery pressure range, disproportional regulating lip deformations occur. In addition, they are difficult to fit or are too noisy in operation.
The problem of the present invention is to improve an apparatus of the aforementioned type in that also in the higher delivery pressure range the flow through a pipe is uniformly throttled or restricted and problem-free fitting and replacement are possible. Moreover, there is to be a relatively large regulating opening, which cannot be clogged by small dirt particles carried along in the water.
This problem is solved by an apparatus of the aforementioned type, in which the throttling insert is constructed symmetrically to a plane passing perpendicularly to a flow limitation and which is provided on both the inflow side and the outflow side with an annular regulating lip. A throttling insert constructed in this way also offers the advantage that as a result of its symmetrical construction, it cannot be incorrectly fitted. Tests have shown that such a throttling insert can also be constructed so as to operate quietly. In addition, the symmetrically designed regulating lips on either side act asymmetrically in operation.
Throttling inserts having a flow channel increasing diameter along the flow path leading to a midpoint and a decreasing diameter past the midpoint, in the unloaded state, the diameter preferably varying continuously, are advantageous. Among these particularly those in which the inner wall of the flow channel is constructed in curved manner in longitudinal section and in preferably arcuately curved, so that a convex or cylindrical passage is obtained, which is bounded at its two openings by the regulating lips, have proved particularly advantageous because they operate quietly and adaptably.
According to a preferred embodiment, the throttling insert is substantially annular and is provided on either end face with an annular slot concentric to the flow channel. Parts of the annular slot wall form the outer wall of the inflow side and/or outflow side regulating lip, the areas of the throttling insert forming the transitions from the annular slots to the flow channel preferably having a cross section essentially corresponding to that of a wedge with a wedge angle of 35.degree. to 50.degree.. The smaller angle, i.e. the lower limit range is suitable for large bores and large throughflows, whereas the smaller wedge angles are intended for narrow flow bores with correspondingly smaller flow quantities. Wedge angles of 35.degree. to 40.degree. permit a relatively large constriction of the flow channel, because the regulating lip can be more strongly wrapped round.
The outside of the regulating lips is preferably constructed so as to correspond to the circumferential surface of a truncated cone, whose axis of symmetry runs in the through-flow direction. This truncated cone preferably extends into the bottom of the particular annular slot.
The side of the regulating lips facing the flow is preferably inclined out of the cross-sectional plane counter to the inflow direction by approximately 20.degree. to 40.degree. and preferably 30.degree., so that quiet throttling is possible, which reacts rapidly to pressure fluctuations. By variation wedge angles and slopes can be so matched to one another that desired characteristics of the throttling action are achieved.
According to a preferred embodiment a thrust ring is associated with the throttling insert and supports the insert radially and axially on the outflow side. This thurst ring can have a bearing shoulder which is essentially adapted to and projects into the outflow side slot profiling of the throttling insert. The thrust ring is preferably constructed in such a way that its bearing shoulder substantially leaves the wedge-shaped part of the outflow side regulating lip unsupported in the state when there is no through-flow. For calming the flow and for soundproofing purposes, the thrust ring can be provided on the outflow side with at least one flow guidance member, which is preferably constructed in one piece therewith. In a preferred embodiment, said flow guidance member is a perforated base plate.
The throttling unit can form together with the thrust ring associated therewith a unit which can be iserted and e.g. slid into a fitting and as such can be easily replaced even by the amateur without the aid of any tools. It is also possible to provide a plurality of throttling inserts having different throttling actions and whose boundary coming to rest on the thrust ring is always the same, so that they can be chosen as a function of the given pressure and flow conditions and can be interchangeably inserted in the thrust ring. The outer faces of the regulating lips form with the circumferential surface of the throttling insert an angle of preferably 50.degree. to 80.degree..